vault Function

Secrets can be read from Vault and used within your template as user variables. the vault function is available only within the default value of a user variable, allowing you to default a user variable to a vault secret.

An example of using a v2 kv engine:

If you store a value in vault using vault kv put secret/hello foo=world, you can access it using the following:

locals {
    foo = vault("/secret/data/hello", "foo")
}

which will assign local.foo with the value "world"

An example of using a v1 kv engine:

If you store a value in vault using:

vault secrets enable -version=1 -path=secrets kv
vault kv put secrets/hello foo=world

You can access it using the following:

locals {
    foo = vault("secrets/hello", "foo")
}

This example accesses the Vault path secret/foo and returns the value stored at the key foo, storing it as the local variable local.foo.

If the Vault secret contains a highly sensitive value the local block, not to be confused with the locals block, can be used to mark the value as sensitive.

local "foo" {
    expression = vault("secrets/hello", "foo")
    sensitive  = true
}

The local block example accesses the Vault path secrets/foo and returns the value stored at the key foo, storing it as the local variable local.foo. However, the output of the newly stored local variable will be filtered from the Packer build output, and replaced with the value <sensitive>. See Local Values for more details.

Usage

In order for the Vault function to work, you must set the environment variables VAULT_TOKEN and VAULT_ADDR to valid values.

NOTE: HCL functions can be used in local variable definitions or inline with a provisioner/post-processor. They cannot be used in global variable definitions.

The api tool we use allows for more custom configuration of the Vault client via environment variables.

The full list of available environment variables is:

"VAULT_ADDR"
"VAULT_AGENT_ADDR"
"VAULT_CACERT"
"VAULT_CAPATH"
"VAULT_CLIENT_CERT"
"VAULT_CLIENT_KEY"
"VAULT_CLIENT_TIMEOUT"
"VAULT_SKIP_VERIFY"
"VAULT_NAMESPACE"
"VAULT_TLS_SERVER_NAME"
"VAULT_WRAP_TTL"
"VAULT_MAX_RETRIES"
"VAULT_TOKEN"
"VAULT_MFA"
"VAULT_RATE_LIMIT"

and detailed documentation for usage of each of those variables can be found here.